Pipe-threading die.



B. BRDBN.

PIPE THRBADING DIE.

APPLICATION FILED MAR. 23, 1910,

LO88,482 Patented sept. 10,1912.

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f @5% a i l'rozu UNITED STATES PATENT OFFICE.

BRADFORD BORDEN,.0ZF TORONTO,` ONTARIO, CANAD, A SSIGNOR TO THE BORDENCOMPANY,. OF WARREN, OHIO, A CORPORATION OF- OHIO.

PIPE-THREADING DIE.

Speciv'cation 'of Letters Patent.

Pacenteasepa 10,1912.

Application. tiled March 23, 1910.V Serial No.- 551,188;

To all fwlwmz't may concern:

Be it known that I, BRADFoRuBoRDEN, of Toronto, in the Province ofOntario and Dominion of Ganada, have invented certain new and usefulImprovements' in Pipe- Threading Dies; and I do hereby declarethefollowing to be a full, clear, and exact description 0f theinvention, such as will enable otherss-k-illed in the art: to which itappertains to make anduse the same.

TheA primary object of this invention is to so arrange the cuttingthreads of threading dies-that engagement with a pipe or bolt nay bereadily initiated and the cutting of a standard thread completed withthe eX- penditure' of less energy than is ordinarily required:withhand-tools. To this end, I arrange the threads of: each die bit orsegment, or thethreads of4 a Chaser, on two planes, the plane oftheinitially-acting or throat threads being. farther from the axis off' thetoolfthan the plane of' the main cutting threads, which. latter threadsare stepped up from the throat threads. The base line offtheinitially-acting threads is preferably straight, that is, parallel`with theaxis of the die or tool, but it may, however, be s et on.aslight taper, that is, at an angle to the tool axis. The plane of thebase-line off the main cutting threads is inset, relatively to thebase-line of the throat threads, and-such main threads are preferablytapered, their plane beingalways nearer the axis ofthe tool-than theini, tially-aeting teeth. By thus forming the die-segments or. chasers,the throat of the tool is enlarged and of substantially unlformdiameter, and the throat threads will out partial threads or gutters,preferably o'n straight lines, and such throatl threads will, unaided byany leader-screw, or its equivalent, hold the tool. to` the. workI asagainst the resistance which occurs in stepping up to the maincuttingthreads. The lutter upon being brought into action, havingto cut to lessdepth, will.follow\ at correetiipitch and with lessenedA resistance inthe partial threads or gutters formed 1n the work by the throat threads.With my invention Iv am enabled to obtain, with a solid ornon-adjustable die stock, the same result as with an adjustabledie-stock going twice over the work, with the dies or chasers setfarther in for the second operatlon. By forming the step up between thethroat threads: and the' main cutting threads, the .respective baselinesbeing on different planes, If am enabled to set the 'throatthreadsoutwardly. sufciently far to insure the die or tool readilytaking hold of the work and hold the die or tool thereto when themain-.threads begin'to act. Without the step up fromone set of threadsto the other the throatithreads would'have to be given a very abrupttaper whichwould be insutlicient, withoutthe aid of a leader-screw orits equivalent, to initiate engagement with the work.

In statingthat the root-s or base lines of the threads ofthe two seriesare on different planes, itis. understood that reference is made alsotothe points of the threads; and although all the threadsvof eachseries. are shown as full threads with knife-like edges, itis to beunderstood that in some instances some ofthe points may be blunted.- Ineither event, however, the Abase lines and points of the threads Off thedifferent series are on.. differentY planes, and the main threads arestepped up fromv the initially acting r threads. Y

The invent-ion will be hereinafter fully set. forth.A and particularlypointed out in the claims.'

In the accompanyingdrawings, Figure 1 is a faceview. and Fig. Qis atransverse sectional view ofasoliddie constructed in accordance with myinvention. Fig. 3 is a view in perspectiveof` a-chaser or segment die.Fig. 4- 1s. aside elevation of a die' on an enlargedI scale. slightmodifications. Fig. 7 shows a 'thread formed bythe soliddieof Figs. 1and 2.

My present improvements are applicable to solid dies;. ad]ustable dies,and chasers capable. of automatically receding during the threadingoperation.

In Figs. l anda@ I havevshown a solid die having, as usual, a. centralopening and a series of'inwardly-projecting threading bits. The .base ofthethreads l. in the throats is outwardly set relatively to the base ofthe main cutting threads 2. In consequence, the 'diameter of the openinof the die is greatfest at, the throat, and" it is thus formed so ,thatthe initially-acting threads will remove comparatively little metal, andwill form on the work but partial threads 0r gutters, being intended tocut inwardly but a third, or less, of the required depth. `The base-lineFigs. 5 and 6 show the main cutting threads.

of these initially-acting threads is preferably straight, on a planeparalleling the axis of the die or tool. B forming the throat on' alsubstantially uni orm enlarged diameter so that the threads thereof willcut practically nothin more than gutters, (in depth but a small act-ionof that required for the completed thread) the die will start easily onits work. It is immaterial how many threads are in the throat, but forall practical purposes I have found that three or four are suiiicient,as even when on a taper they will all hold the pipe equally against theincreased resistance offered by the main threads when the step-up ismade thereto. y

' The base of the rnain cutting threads 2 is iii-set on a differentplane from the base of the initially-acting threads, so: that thedieopening is, throughout the length of the main threads, of lessdiameter than at its throat. The base of the second series of threads isset on a taper,'and the base ofthe initially-acting threads may also beon-,aI taper (Fig. 5) but such latter taper must not, in order to obtainthe advantages of my invention, be very abrupt. It 1s not necessary,however, that the second series be tapered, since, as shown in Fig. 6,-,such threads may be straight and on a plane arallel with the rst-actingseries. This 1s ldesirable for threading bo ts.

In'practice, starting the die or tool on the work is'comparatlvel-y easyon account 'of' the small amount of metal which the first series ofthreads are required to remove. The latter, although practicallycomplete threads, form only gutters or partial threads in the pipe,being out-set to a degree which enables them to readily take hold of thework, The main cutting threads, when the step-up is made thereto,t'ravel in the gutters or partial threads on the pipe, and complete astandard tapler thread. The initiallyacting threads, in t e throat ofthe die, ordinaril make but one-third of a cut, or less, but t ey holdthe tool to the work as against the increased resistance in stepping upto As the latter follow in the gutters .or partial grooves formed by thefirst series of threads, the standard thread ma be cut with lessexertion than if all te Chaser-threads were cut on a continuous taper,and starting is far easier than if the first series of threads mainthreads.AV

In using an adjustable die-stock with dies having straight threads, tomake starting easy the dies are irst'set to cut about onethird therequired depth, and then after this operation is completed the dies areadjusted to standard. The stock will then start on the work withcomparative ease on account of the partial vthreads previously formed.The result of the double operation of an adjustable die-stock isattained by forming the dies as hereinbefore described, the first seriesof threads effecting an easy starting, and forming partial threads orgutters in which the second series of threads follow to cut to standardtaper.- I am thus enabled to obtain in one operation the same result asin two operations of, an adjustable die-stock.

Theadvantages of ymy invention will be apparent to those skilled intheart. By so forming the threads of a pipe 'or bolt threading die that theplane of the baseline of the initially-acting threads is always outsidethe plane of the base-line of the finishing threads, whether the formerthreads are on straight lines or on a taper, I am enabled, to obtain an.easy-working die capable of readily initiating the threading operationand making the completion of the thread cutting comparatively easy.

I claim as `my l invention 1. A die formed with a cutting face having aseries of threads in its throat, and a series of main cutting threads,the roots or base lines of the threads of the two series being ondifferent planes, and the main threads step ed u from the throatthreads.

2. Afdie orme with a cutting face having a series of threads in itsthroat Whose base line is on a plane substantially parallel with theaxis of the die, and a series of main threads whose base line and pointsare on" with the axis of the die, and a series of main threads whosebase line and points are at acute angles to the rst mentioned threads.In testimony whereof, I have signed this .specification in the presenceof two subscribing witnesses.

BRADFORD BORDEN. Witnesses: i

FRANCES. MAGUIRE, J oHN A. MURPHY.

